1. Technical Field
This invention relates generally to physical management of flexible substrates. More particularly, the present invention relates to an apparatus and method for easy yet precisely controlled fixturing, tensioning, and ancillary processing of flexible substrates for fabrication and assembly of surface mount products or processing steps there between.
2. Related Art
Flexible substrates are utilized in many different applications and it is often necessary to physically manage how flexible substrates are handled. A common handling method involves mounting a flexible substrate to a split frame and then tensioning the substrate by virtue of stretching the split frame. In order to reduce possible distortion of the flexible substrate when it is tensioned by a split frame, it often necessary for the frame to include means to flatten the flexible substrate prior to mounting the substrate onto the frame. However, flattening a substrate prior to mounting is not always feasible because flattening involves additional handling steps adding to handling complexity. Moreover, flattening prior to mounting is often time unsuitable for delicate substrates which may break or distort due to forces applied during flattening or deform because of forces generated by distorted flattening means of the frame. Frames without flattening means do not correct substrate distortions by flattening the flexible substrate prior to mounting. Another common substrate handling method involves mounting the material to a frame that exhibits an equal or higher coefficient of thermal expansion (“CTE”) to that of the substrate material. Thus, when heated, the frame material expands faster than the substrate and the flexible substrate becomes tensioned. Yet, this thermally relative substrate handling method often requires exotic frame materials, which can be expensive. In addition a mismatch of the CTE of the substrate material to the CTE of the frame material may also lead to breakage or distortion of the flexible substrate. Still another known flexible substrate handling method is to laminate the substrate material onto a rigid frame for processing. This more permanent handling method, however, may limit the post-processing options because of the laminate.
Therefore, there exists a need for an apparatus and method for reliably tensioning a flexible substrate to remove undesirable defects, such as wrinkles or other non-planar conditions that may be introduced as a result of fabrication, mounting, or other operations. The presently disclosed improvement allows for accurate, controlled, and reproducible registration of the flexible substrate for patterning, printing, placement, reflow, deposition, or any other standard assembly technique requiring precise registration and/or use of a vision system.